Influence of the incoming solar radiation on the bone mineral density in the female adult population in Croatia

The relationship between the bone mineral density (BMD) in Croatian female adults and the average incoming solar radiation at the ground was investigated. The study included 387 volunteers of average age of 60 years from three different towns: Pula (n = 128, age from 35 to 76), Krapina (n = 141, age from 43 to 77), and Zagreb (n = 118, age from 32 to 79). Apart from the different lifestyle, each of above towns is characterized by different incoming solar radiation, where values of 503.3 kJ cm-2, 471.2 kJ cm-2 and 436.3 kJ cm-2 correspond to average annual radiation at the ground for Pula, Krapina and Zagreb, respectively. Heel BMD was measured by clinical bone sonometer (Sahara). On the average the BMD was highest for Pula (0.469 g cm-2) and the lowest for Zagreb (0.433 g cm-2). Similarly, the percentage of normal bones was the highest for Pula (46.1%) and the lowest for Zagreb (32.2%). Osteopenic bones were the most frequent for Zagreb (61.0%), while corresponding figures for Pula and Krapina were 46.9% and 43.6%, respectively. Osteoporosis varied from 6.8% in Zagreb to 11.4% in Krapina. A test of independence by contingency table confirmed at the significance level alpha = 0.05 that probability of normal bone occurrence increases with the increase of incoming solar radiation. Results of the multiple regression analysis suggest the dependence of BMD on woman's age and weight, and incoming solar radiation at the place of habitation.     

Phylogeny of vertebrate nuclear receptors--analysis of variance components in protein sequences

Nuclear receptors (NR) constitute a large family of proteins and play a crucial role in regulating mineral metabolism and physiological homeostasis of various organ systems. The aim of this study was to elucidate whether the variance among NRs of estrogen, androgen and vitamin-D in various vertebrate species including humans is attributed to differences between the taxonomic groups within a specific receptor (i.e. between orthologous) or between the different proteins within the taxon (i.e. between paralogous genes). Published data on 57 protein sequences of the above NRs were used for phylogenetic analysis. The results showed that in DNA- and ligand-binding regions, 94% and 70% of variance is due to differences between the three proteins. However, in non-binding regions, 47% of the variance results from differences between the three paralogous proteins. Human sequences consistently clustered with their mammal orthologous within the three groups of NR sequences, clearly indicating that evolution of human sequences is not distinct from mammal sequence evolution.     

Variation in the HLA-G promoter region influences miscarriage rates

The HLA-G gene is primarily expressed in placental cells that invade the maternal decidua during pregnancy. This gene encodes multiple isoforms that fulfill a variety of functions at the maternal-fetal interface throughout gestation. Recently, a null allele for the most abundant HLA-G isoform was associated with recurrent miscarriage in two independent studies, suggesting that reduced levels of the HLA-G1 protein may compromise successful pregnancy. We initiated the present study to determine whether other polymorphisms that could affect expression levels of HLA-G were associated with fetal loss in women participating in a 15-year prospective study of pregnancy outcome. We genotyped these subjects for 18 single-nucleotide polymorphisms in the 1,300 bp upstream of exon 1, 13 of which were identified as part of this study, as well as for an insertion/deletion (in/del) polymorphism in the 3' untranslated region. The 18 SNPs defined eight unique haplotypes. One polymorphism, -725C/G, was associated with fetal loss, with an increased risk for miscarriage in couples in which both partners carried the -725G allele, compared with couples not carrying this allele (odds ratio 2.76, 95% confidence interval 1.08-7.09; P=.035). Further, the G at nucleotide -725 creates a CpG dinucleotide, and we demonstrate that this CpG site is methylated on -725G alleles. Overall, this study identified extraordinary levels of variation in the 5'-upstream regulatory region of HLA-G and provides evidence for an association between a promoter-region SNP and fetal loss rates, further attesting to the novel features and critical role of this gene in pregnancy.     

Improper chromosome synapsis is associated with elongated RAD51 structures in the maize<Emphasis Type="Italic"> desynaptic2</Emphasis> mutant

The RecA homolog, RAD51, performs a central role in catalyzing the DNA strand exchange event of meiotic recombination. During meiosis, RAD51 complexes develop on pairing chromosomes and then most disappear upon synapsis. In the maize meiotic mutant desynaptic2 (dsy2), homologous chromosome pairing and recombination are reduced by ~70% in male meiosis. Fluorescent in situ hybridization studies demonstrate that a normal telomere bouquet develops but the pairing of a representative gene locus is still only 25%. Chromosome synapsis is aberrant as exemplified by unsynapsed regions of the chromosomes. In the mutant, we observed unusual RAD51 structures during chromosome pairing. Instead of spherical single and double RAD51 structures, we saw long thin filaments that extended along or around a single chromosome or stretched between two widely separated chromosomes. Mapping with simple sequence repeat (SSR) markers places the dsy2 gene to near the centromere on chromosome 5, therefore it is not an allele of rad51. Thus, the normal dsy2 gene product is required for both homologous chromosome synapsis and proper RAD51 filament behavior when chromosomes pair. Edited by: P. Moens     

Effects of temperature on phyllody expression and cytokinin content in floral organs of rose flowers

Formation of leaf-like organs known as phylloids in Rosahybrida cv. Motrea flowers was promoted by exposure of plants toelevated temperatures. At a day/night temperature regime of26°C/21°C respectively theproportion of malformed flowers exhibiting phyllody was four times higher thanthat in flowers of plants grown at21°C/15°C. The number ofpetals in phyllody-expressing flowers was higher than that in normal flowers.The total content of endogenous cytokinins in young flower buds of plantsexposed to the lower temperature was six times higher than that at the highertemperatures. The effects of the reduced temperature were pronounced on all thegroups of cytokinins examined. However, the proportion of the various cytokiningroups remained similar at both temperature regimes. In contrast to thecytokinins in the flower buds, the content of all cytokinin types in youngleaves increased following exposure to the higher temperature and was reducedbythe lower temperatures. After 11 weeks at the lower temperature, about18% of the flowers remained malformed, whereas at the higher temperatureabout 20% of the flowers still remained normal. All thephyllody-exhibiting flowers were formed on vigorously grown basal shootscharacteristic to Rosa hybrida plants, whereas the normalflowers at the elevated temperatures were formed on lateral shoots which weremost distal to the plant base. However, irrespective of the season, thepresenceof normal and malformed flowers was observed on plants kept growing at standardconditions of 30°C/17°C inthegreenhouse. This phenomenon led us to examine the cytokinins in floral organsofnormal and malformed cv. Motrea flowers grown in the greenhouse as well as inflowers of a complete rose mutant known as a 'Green Rose(Rosa chinensis viridiflora). The highest content ofcytokinins was found in the pistils and stamens of normal 'Motreaflowers. On the other hand, the content of cytokinins in leaf-like style-tubesin the malformed flowers as well as in partially malformed ovaries at the baseof phylloids was significantly lower. A low content of cytokinins was alsopresent in petals of both normal and phyllody-exhibiting flowers and the lowestcontent has been found in the phylloids of the 'Green Rose. Apossibility of mutant deviations in metabolism of cytokinins in rose plants isdiscussed.     

Structure-function relationships in the integument of Salamandra salamandra during ontogenetic development

Morphological, cytological and transport properties of the integument of Salamandra salamandra were investigated during natural ontogenetic development, from birth to adult. Three stages were operationally defined: I, larvae, from birth to metamorphosis; II, metamorphosis (judged externally by the colour change and loss of the gills); and III, post-metamorphosis to adult. Pieces of skin were fixed at various stages for immunocytochemical examinations, and the electrical properties were investigated on parallel pieces. Distinct cellular changes take place in the skin during metamorphosis, and lectin (PNA, WGA and ConA) binding indicates profound changes in glycoprotein composition of cell membranes, following metamorphosis. Band 3 and carbonic anhydrase I (CA I) were confined to mitochondria-rich (MR)-like cells, and were detected only in the larval stage. CA II on the other hand, was detected both in MR-like and in MR cells following metamorphosis. The electrical studies show that the skin becomes more tight (transepithelial resistance increases) upon metamorphosis, followed by manifestation of amiloride-sensitive short-circuit current (I(SC)) indicating that functional Na+ uptake has been acquired. The skin of metamorphosed adults had no finite transepithelial Cl- conductance, and band 3 was not detected in its MR cells. The functional properties of MR-like and MR cells remain to be established.     

Novel group I intron in the tRNA(Leu)(UAA) gene of a gamma-proteobacterium isolated from a deep subsurface environment

A group I intron has been found to interrupt the anticodon loop of the tRNA(Leu)(UAA) gene in a bacterium belonging to the gamma-subdivision of Proteobacteria and isolated from a deep subsurface environment. The subsurface isolate SMCC D0715 was identified as belonging to the genus Pseudomonas. The group I intron from this isolate is the first to be reported for gamma-proteobacteria, and the first instance of a tRNA(Leu)(UAA) group I intron to be found in a group of bacteria other than cyanobacteria. The 231-nucleotide (nt) intron's sequence has group I conserved elements and folds into a bona fide group I secondary structure with canonical base-paired segments P1 to P9 and a paired region, P10. The D0715 intron possesses the 11-nt motif CCUACG. UAUGG in its P8 region, a feature not common in bacterial introns. To date, phylogenetic analysis has shown that bacterial introns form two distinct families, and their complex distribution suggests that both lateral transfer and common ancestry have taken part in the evolutionary history of these elements.     

A role for CCR9 in T lymphocyte development and migration

CCR9 mediates chemotaxis in response to CCL25/thymus-expressed chemokine and is selectively expressed on T cells in the thymus and small intestine. To investigate the role of CCR9 in T cell development, the CCR9 gene was disrupted by homologous recombination. B cell development, thymic alphabeta-T cell development, and thymocyte selection appeared unimpaired in adult CCR9-deficient (CCR9(-/-)) mice. However, competitive transplantation experiments revealed that bone marrow from CCR9(-/-) mice was less efficient at repopulating the thymus of lethally irradiated Rag-1(-/-) mice than bone marrow from littermate CCR9(+/+) mice. CCR9(-/-) mice had increased numbers of peripheral gammadelta-T cells but reduced numbers of gammadeltaTCR(+) and CD8alphabeta(+)alphabetaTCR(+) intraepithelial lymphocytes in the small intestine. Thus, CCR9 plays an important, although not indispensable, role in regulating the development and/or migration of both alphabeta(-) and gammadelta(-) T lymphocytes.     

Accumulation of arachidonic acid-rich triacylglycerols in the microalga Parietochloris incisa (Trebuxiophyceae,Chlorophyta)

The freshwater green microalga Parietochloris incisa is the richest known plant source of the polyunsaturated fatty acid (PUFA), arachidonic acid (20:4omega6, AA). While many microalgae accumulate triacylglycerols (TAG) in the stationary phase or under certain stress conditions, these TAG are generally made of saturated and monounsaturated fatty acids. In contrast, most cellular AA of P. incisa resides in TAG. Using various inhibitors, we have attempted to find out if the induction of the biosynthesis of AA and the accumulation of TAG are codependent. Salicylhydroxamic acid (SHAM) affected a growth reduction that was accompanied with an increase in the content of TAG from 3.0 to 6.2% of dry weight. The proportion of 18:1 increased sharply in all lipids while that of 18:2 and its down stream products, 18:3omega6, 20:3omega6 and AA, decreased, indicating an inhibition of the Delta12 desaturation of 18:1. Treatment with the herbicide SAN 9785 significantly reduced the proportion of TAG. However, the proportion of AA in TAG, as well as in the polar lipids, increased. These findings indicate that while there is a preference for AA as a building block of TAG, the latter can be produced using other fatty acids, when the production of AA is inhibited. On the other hand, inhibiting TAG construction did not affect the production of AA. In order to elucidate the possible role of AA in TAG we have labeled exponential cultures of P. incisa kept at 25 degrees C with [1-14C]arachidonic acid and cultivated the cultures for another 12 h at 25, 12 or 4 degrees C. At the lower temperatures, labeled AA was transferred from TAG to polar lipids, indicating that TAG of P. incisa may have a role as a depot of AA that can be incorporated into the membranes, enabling the organism to quickly respond to low temperature-induced stress.